Exhaust idea

[Ciro Pabón]

marekk, I got it the other way. Intake temp on the turbine is 1200, we agree on that. Exhaust temperature of the turbine would be 850 K.

So, the difference is temperature is 350

Although, given that it is raining and I have to work a lot, it should be 555.55, you know, for inspiration.

The work you do with this gadget depend on that temperature difference.

Anyway, thanks for reading what I wrote, marekk, and correct me again if I did not get your point, please.

To get a turbine exhaust temperature of 350 degrees (thus, a difference in temperature of 850 degrees) you need way more than the 4 bars to 1 bar difference in pressure I assumed.

I repeat, for Manchild's benefit, the main assumption here is the pressure you get at the engine exhaust exit. This is the key for your turbine. If you want to know how feasible is this "engine within an engine" idea of yours (or dual cycle engine, better yet) you need to find a true number for this exit pressure of the gasoline engine exhaust.

The difference between this exit pressure and the ambient pressure gives you the difference in temperature between intake and outtake of turbine, using the equation I posted: T2/T1 = (P2/P1)^(1-1/Gamma), where Gamma is around 1.4 for gas turbines.

With this difference in temperature plus the flow of air plus the specific heat capacity (Cp) you get the work done, and multiply it by an efficiency factor (isentropy), or Work = flow * Cp * Delta Temperature * efficiency, and that's, I think, the answer to your question.

Going into personal detail, I'm alone, Manchild, btw, no girls around. I weren't doing thermodynamic calculations if there were any. I'm a single parent, you know I'm entirely devoted to my kids (they are with their mom right now). Oh, and all the flag commentaries were just a joke (but I see many of those in your future... ). You know I also love "Imagine".

On the other hand, thinking about this for a moment, Manchild, I think that the back pressure that the turbine would create on the engine, would diminish the efficiency of the Otto cycle. You know better than me than an Otto engine is basically an air pump, moved by gasoline. So, I think we need more calculations, friend.

Anyway, I'd gues we're talking of 100 extra HP at full power, but I'm not sure, we need an Otto engine specialist here and I'm not one.

Notice that as the pressure and temperature are related in an exponential way (ratio of exit/intake temperature is cubic root of pressure ratio, give or take: the actual exponent is a tad under 0.3) I think you would notice a huge "kick in" when giving full throttle, as in regular turbos.

I think that's the reason why gas turbines in electric generation are kept in a narrow rpm range: they are designed for the optimum energy extraction.

Actually, we need a mechanical engineer here, but you know how lazy those guys are...

[manchild]

Another thought that crossed my mind.

Engaged only at full power, agreed.

Speaking of exhaust cycle as one of 4 cycles of Otto engine, with some clever engineering and variable geometry turbine it could be set to aid the process of exhaust on lower rpm/power.

Yes, we need engineer here.

How it could aid this process while it is not engaged? Well, since it would be connected to gearbox's input shaft, on lower revs/lower power it could suck the gasses out of exhaust manifold. Same thing as Brabham fan car, only turbine instead of fan, and suction of exhaust gasses instead of air below the car.

[bhall]

Can we assume that such an idea is illegal because teams aren't presently doing anything to harness the ~185 HP (cheers) per Ciro's calculations? That seems like an awful lot of power left untapped if it's allowed.

Or am I just making the tacit assumption that F1 teams are clever enough to have already thought of this?

[ringo]

Just a slight correction. The efficiency is temperature dependent but the power output is pressure dependent.

One draw back with a crankshaft turbine is that it will spin at relatively low speeds and at varying speeds. It might have to be of a biggish size to have a decent average efficiency.
Wheel shaft turbine are probably worse as they will spin much slower and different speeds per side in turns; not sure how that will affect the engine pulses.

I would say there is about 223hp to be gained from the exhaust with an 85% efficiency turbine.
KERS can be retired now.

[marekk]

Ciro,
it's my poor english i suppose.
I perfectly agree on your calculations regarding turbines power output and adiabatic process equations.
I've just wanted to mention, that after doing the job on turbine blades, there is still a lot of energy in exhaust gases.
One can radiate it for example to bridge this cruel gap between shirtless people enjoing 300K and not so happy ones freezing at 280K

The point is, 185HP is a lot of power to compress the air and influence car's aerodynamics, if used at varius places to control the flows.

@manchild - AFAIK, high pressure exhaust pulses are followed by low pressure (near vacuum) pulses. Exhaust systems are already tuned to benefit from this - vacuum sucks the gasses from cylinders. So probably no big gains to achive from this idea.

[manchild]

I've forgot to mention the reductor. A tiny CVT connecting turbine axle and input shaft or crankshaft. It would be a necessity for more sophisticated use.

[Formula None]

ARTICLE 5 : ENGINES AND KINETIC ENERGY RECOVERY SYSTEMS

5.1 Engine specification :

5.1.1 Only 4-stroke engines with reciprocating pistons are permitted.
5.1.2 Engine capacity must not exceed 2400cc.
5.1.3 Crankshaft rotational speed must not exceed 18,000rpm.
5.1.4 Supercharging is forbidden.
5.1.5 All engines must have 8 cylinders arranged in a 90º “V” configuration and the normal section of each
cylinder must be circular.
5.1.6 Engines must have two inlet and two exhaust valves per cylinder.
Only reciprocating poppet valves are permitted.
The sealing interface between the moving valve component and the stationary engine component must be
circular.

5.2 Other means of propulsion :

5.2.1 The use of any device, other than the 2.4 litre, four stroke engine described in 5.1 above and one KERS, to
power the car, is not permitted.
5.2.2 With the exception of one fully charged KERS, the total amount of recoverable energy stored on the car
must not exceed 300kJ. Any which may be recovered at a rate greater than 2kW must not exceed 20kJ.
5.2.3 The maximum power, in or out, of any KERS must not exceed 60kW.
Energy released from the KERS may not exceed 400kJ in any one lap.
Measurements will be taken at the connection to the rear wheel drivetrain.
5.2.4 The amount of stored energy in any KERS may not be increased whilst the car is stationary during a race
pit stop.
Release of power from any such system must remain under the complete control of the driver at all times
the car is on the track.
5.2.5 Cars must be fitted with homologated sensors which provide all necessary signals to the SDR in order to
verify the requirements above are being respected.

5.3 Engine dimensions :

5.3.1 Cylinder bore diameter may not exceed 98mm.
5.3.2 Cylinder spacing must be fixed at 106.5mm (+/- 0.2mm).
5.3.3 The crankshaft centre line must not be less than 58mm above the reference plane.

5.4 Weight and centre of gravity :

5.4.1 The overall weight of the engine must be a minimum of 95kg.
5.4.2 The centre of gravity of the engine may not lie less than 165mm above the reference plane.
5.4.3 The longitudinal and lateral position of the centre of gravity of the engine must fall within a region that is the
geometric centre of the engine, +/- 50mm. The geometric centre of the engine in a lateral sense will be
considered to lie on the centre of the crankshaft and at the mid point between the centres of the forward
and rear most cylinder bores longitudinally.
5.4.4 When establishing conformity with Articles 5.4.1, 5.4.2, 5.4.3 and Appendix 4 of the F1 Sporting
Regulations, the homologated engine will include the intake system up to and including the air filter, fuel
rail and injectors, ignition coils, engine mounted sensors and wiring, alternator, coolant pumps and oil
pumps.
5.4.5 When establishing conformity with Article 5.4, the engine will not include :
- clutch and clutch actuation system ;
- flywheel ;
- electronic control units or any associated devices containing programmable semiconductors ;
- the alternator regulator ;
- liquids ;
- exhaust manifolds ;
- heat shields ;
- oil tanks, catch tanks or any breather system connected to them ;
- studs used to mount the engine to the chassis or gearbox ;
- water system accumulators ;
- heat exchangers ;
- hydraulic system (e.g. pumps, accumulators, manifolds, servo-valves, solenoids, actuators) except
servo-valve and actuator for engine throttle control ;
- fuel pumps nor any component not mounted on the engine when fitted to the car.
- any ancillary equipment associated with the engine valve air system, such as hoses, regulators,
reservoirs or compressors.
Furthermore, any parts which are not ordinarily part of an engine will not be included when assessing its
weight. Examples of this could be, but are not limited to :
- Wiring harnesses having only a partial association with engine actuators or sensors ;
- A bell housing designed to be integral with the engine crankcase ;
- Top engine mountings designed higher than necessary with integral webs or struts. The centre of
any engine mounting which is part of a cam cover should not be any more than 100mm above a
line between the camshaft centres, when measured parallel to it. Any webs integral with the cam
cover should not extend further back than the centre of the second cylinder bore ;
- Ballast. This is permitted on the engine (subject to the requirements of Article 4.2) but any in excess
of 2kg will be removed from the engine before measuring engine weight or centre of gravity height.

5.5 Engine throttles :

5.5.1 The only means by which the driver may control the engine throttle positions is via a single chassis
mounted foot pedal.
5.5.2 Designs which allow specific points along the pedal travel range to be identified by the driver or assist him
to hold a position are not permitted.
5.5.3 The minimum and maximum throttle pedal travel positions must correspond to the engine throttle minimum
(nominal idle) and maximum open positions.

5.6 Exhaust systems :

Engine exhaust systems may incorporate no more than two exits.

5.7 Variable geometry systems :

5.7.1 Variable geometry inlet systems are not permitted.
5.7.2 Variable geometry exhaust systems are not permitted.
5.7.3 Variable valve timing and variable valve lift systems are not permitted.

5.8 Fuel systems :

5.8.1 The pressure of the fuel supplied to the injectors may not exceed 100 bar. Sensors must be fitted which
directly measure the pressure of the fuel supplied to the injectors, these signals must be supplied to the
FIA data logger.
5.8.2 Only one fuel injector per cylinder is permitted which must inject directly into the side or the top of the inlet
port.

5.9 Electrical systems :

5.9.1 Ignition is only permitted by means of a single ignition coil and single spark plug per cylinder. The use of
plasma, laser or other high frequency ignition techniques is forbidden.
5.9.2 Only conventional spark plugs that function by high tension electrical discharge across an exposed gap are
permitted.
Spark plugs are not subject to the materials restrictions described in Articles 5.14 and 5.15.
5.9.3 Other than for the specific purpose of powering KERS components, the primary regulated voltage on the
car must not exceed 17.0V DC. This voltage is defined as the stabilised output from the on-car charging
system.
With the exception of any KERS or capacitor circuitry or coils being used solely to provide ignition, any
device with a current requirement greater than 50mA or a power requirement greater than 1W may only be
supplied at or below the primary regulated voltage.
Only capacitor discharge ignition systems (those which generate a spark by means of closing a switch
which then discharges a capacitor through the primary side of the ignition coil), are permitted to provide a
voltage higher than the primary regulated voltage to an ignition coil.
Other than any parts being used to supply a higher voltage to devices such as those described in the
previous paragraphs, no device may step up or increase the primary regulated voltage.

5.10 Engine actuators :

With the following exceptions hydraulic, pneumatic or electronic actuation is forbidden :
a) Electronic solenoids uniquely for the control of engine fluids ;
b) Components providing controlled pressure air for a pneumatic valve system ;
c) A single actuator to operate the throttle system of the engine ;
d) Any components required as part of a KERS.
5.11 Engine auxiliaries :
With the exception of electrical fuel pumps engine auxiliaries must be mechanically driven directly from the
engine with a fixed speed ratio to the crankshaft.
5.12 Engine intake air :
5.12.1 Other than injection of fuel for the normal purpose of combustion in the engine, any device, system,
procedure, construction or design the purpose or effect of which is any decrease in the temperature of the
engine intake air is forbidden.
5.12.2 Other than engine sump breather gases and fuel for the normal purpose of combustion in the engine, the
spraying of any substance into the engine intake air is forbidden.

Maybe there's room inside the KERS regs for loopholes (I believe 747heavy drew attention to this in another thread):

1.20 Kinetic Energy Recovery System (KERS)
A system that is designed to recover kinetic energy from the car during braking, store that energy and
make it available to propel the car.

9.2 Clutch control :
The following applies only to the main drivetrain clutch or clutches, any clutch used exclusively as part of a
KERS is exempt.
9.2.1 If multiple clutch operating devices are used, they must all have the same mechanical travel characteristics
and be mapped identically.

9.4 Clutch disengagement :
All cars must be fitted with a means of disengaging the clutch for a minimum of fifteen minutes in the event
of the car coming to rest with the engine stopped. This system must be in working order throughout the
Event even if the main hydraulic, pneumatic or electrical systems on the car have failed. This system must
also disconnect any KERS system fitted to the car.

9.9 Kinetic Energy Recovery System :
9.9.1 The KERS must connect at any point in the rear wheel drivetrain before the differential.

[Formula None]

I think any moving parts in the exhaust system may fall foul of:

5.7.2 Variable geometry exhaust systems are not permitted.

But what is variable geometry? Could you maintain constant volume/surface area and still be legal? Or does a part moving about an axis (turbine) also imply changing geometry?

[bot6]

I think any moving part implies a change in geometry as such.

Good idea, but unfortunately not legal. Still, it might be an interesting concept for road cars, especially on hybrids as a way to further improve the thermic - electric mode...

[Ciro Pabón]

Well, bot6, the meaning of legal depends on how good your lawyer is (or so says my mom, who is a lawyer). I'd argue that the geometry is constant. I think this rule was made to forbid the variable length trumpets of yore or exhaust optimized for length. For example: viewtopic.php?f=4&t=6323

However, even if we can argue for 30 pages over this (and I won't, I just condense 30 pages in two posts as long as the Bible), I think this goes against half the rules kindly posted by FormulaNone and it's too innovative for F1. Formula One is not Le Mans Engineering Efficiency Prize (the most coveted prize to me). Just in case, those are the winners in past years, what I call the thermodynamic masters:

http://www.lemanslive.com/en/24h-mans/2 ... ergetique/

We also had a thread on the BMW system for exhaust energy recovery. It works with a steam engine, btw. I also think FIA has toyed with this idea (exhaust energy recovery), as a complement to KERS, I read about it sometime somewhere (big help, I know).

You know, Manchild is always ahead of his time. I can attest he has invented (or pretended to) the Ferrari nose slot, the slotted vertical panels in rear wing and the frontal exhaust system. The legend says he was born before his mom got pregnant, for example. He waves his flag but nobody sees it....

[manchild]

Yeah, I'm cursed.

Ciro forgot to mention blown rear wing I came up with in 2006. which became reality in 2010. viewtopic.php?f=6&t=2828&start=51

or fully undercut sidepods I came up with in 2005. which became reality on STR in 2011. viewtopic.php?f=6&t=1350

Some are yet to come alive...

[SpeedWanker]

http://en.m.wikipedia.org/wiki/Turbo-compound_engine

[Tommy Cookers]

Having aired a parallel concept in another thread, I shall be studying this one !

But IMO it is important to remember that the later large aircraft engines had been developed to do two different tasks (via WW2).

The first task was to produce a very high short duration maximum power regardless of anything else, by using an artificially low compression ratio at the piston to allow very high induction pressures (this need despite fuel optimised for gains at very rich mixtures and use of ADIs). The Turbo-Compound used only 5:1 CR (allowing 68" Hg induction pressure), so the exhaust was far more energetic than an F1 engine with 13 or 14:1 CR. (Allison used 100-108" induction).
This waste energy was in part recoverable by tubocharging, turbocompounding, or by jet effect, or some combination of these.

The second task (unimportant in many applications) was efficient cruise at lower powers, by greatly overgearing aerodynamically (the propellor is an aerodynamic overdrive CVT), lowering the revs and the induction pressure,and leaning the mixture. The TC was designed around applications where this task was important, ie very long range. The PR turbines were recovering a relatively high power in cruise, generally exhausting (due to the altitude) down to about 0.35 atm abs.

So my perennial question is .......

Is there enough waste energy in F1 exhaust gas to be usefully recovered by compounding via a PR turbine ? (or by a Comprex type device ?)

In this regard (working from in-cylinder indicator diagrams)a value of mean exhaust pressure considered as available throughout the exhaust part of the cycle to an unloaded PR turbine is surely only about 2.5 atm gauge?.
This is equivalent to some (much lower) continuous pressure that corresponds to the 'real' (ie potentially useable) waste power in the exhaust, as BMEP corresponds to the real power of the engine.

The temperature/pressure conditions at exhaust valve opening fall very rapidly, so are unrepresentative of the conditions available to the PRT. The PRT is being fed (intermittently) by a cyclic process, this is not a continuous flow process. There is substantial flow within the exhaust period at little pressure, ie on the upstroke.

LATER NOTE
Even the above value is optimistic, when fundamentals and real data are considered.
The exhaust valve opens when cylinder pressure is high enough(5-6 atm) to try to drive the exhaust supersonically through the port, ie at this moment most of this pressure is lost across the port.This is why we have silencers/mufflers on our road cars ?
Actual measurements below the port show pressures well below 1 atm gauge at best, ie an equivalent continuous figure of less than 0.5 atm gauge. This suggests a potential 2-3% gain in max power.

Engine design is a compromise, can anyone design a PRT that acts as an exhaust valve (at 18000 rpm) ?


Ideally the turbine would be large enough to use this available pressure, even when loaded to recover power, so realising a good proportion of the potential power gain. Any practical (compact) PRT would mainly recover power by causing the upstream exhaust pressure to rise, reducing power delivered by the pistons, and realise only a small gain.

The naturally aspirated engine with turbocompounding makes the supercharged equivalent (and the turbocharged engine) look very good.

There must be some reason why we don't have PRTs in our everyday NA cars !

[matt21]

Is it possible to use a turbocharger to create some high-energy airflow in order to blow the diffusor?
Or will this fall under the rule of no moveable aerodynamic devices?

[machin]

because the turbo removes energy from the exhaust I would suggest the exhaust from a turbo engine is not as useful as the exhaust from the current non-turbos... plus I suspect the FiA will maintain their current exhaust outlet pipe positioning rules....